Curse you, Perry the Platypus! is the one of the most notable running gags and catchphrases.
When Doofenshmirtz is defeated, he yells "Curse you, Perry the Platypus!" before the end of an episode.
Dr. Doofenshmirtz: It's no use, it's no use, we are doomed! You did it! You saved us, Perry the...(Tin foil ball crashes into the building)
Dr. Doofenshmirtz: Curse you, Perry the Platypus!
- In Phineas and Ferb's Quantum Boogaloo where Perry was unable to catch the helicopter and gets hit by the tin foil ball because the air force team was notified to get Phineas and Ferb busted after the Future Candace revealed Linda the rollercoaster, Doofenshmirtz instead jumps to the lower roof unharmed and then yells "I'm Alive" making that be heard after returning from the bad future.
Dr. Doofenshmirtz: It's no use, it's no use, we are doomed!
Intercom: This is Base to Chopper One, some kids built a rollercoaster through downtown, it's video.
Doofenshmirtz: AAH! (Perry locks the Drill-inator's target onto the Old Reliable Geyser and jumps off) Wait, where are you going? AAH! (The Drill-inator lands on the geyser) I'm okay, I -- (spins around and gets flung away) AAH! Fie upon you, Perry the Platypuuuuus!